progress

compiler/ast.go

@@ -57,7 +57,7 @@ type InsertStmt struct {
 
 // Expr defines the interface of an expression.
 type Expr interface {
-	Type() string
+	Type() string // TODO this pattern may not be the best
 }
 
 // BinaryExpr is for an expression with two operands.

compiler/lexer.go

@@ -80,19 +80,19 @@ var keywords = []string{
 
 // Operators where op is operator.
 const (
-	opAdd = "+"
 	opSub = "-"
-	opMul = "*"
+	opAdd = "+"
 	opDiv = "/"
+	opMul = "*"
 	opExp = "^"
 )
 
 // operators is a list of all operators.
 var operators = []string{
-	opAdd,
 	opSub,
-	opMul,
+	opAdd,
 	opDiv,
+	opMul,
 	opExp,
 }
 

compiler/parser.go

@@ -196,8 +196,8 @@ func (p *parser) getOperand() (Expr, error) {
 		return &IntLit{Value: intValue}, nil
 	}
 	if first.tokenType == tkIdentifier {
-		dot := p.peekNextNonSpace()
-		if dot.tokenType == tkSeparator {
+		next := p.peekNextNonSpace()
+		if next.tokenType == tkSeparator {
 			p.nextNonSpace()
 			prop := p.peekNextNonSpace()
 			if prop.tokenType == tkIdentifier {
@@ -208,7 +208,9 @@ func (p *parser) getOperand() (Expr, error) {
 				}, nil
 			}
 		}
-		return nil, errors.New("failed to parse identifier")
+		return &ColumnRef{
+			Column: first.value,
+		}, nil
 	}
 	// TODO support unary prefix expression
 	// TODO support parens

planner/select.go

@@ -1,6 +1,8 @@
 package planner
 
 import (
+	"slices"
+
 	"github.com/chirst/cdb/compiler"
 	"github.com/chirst/cdb/vm"
 )
@@ -84,7 +86,12 @@ func (p *selectQueryPlanner) getQueryPlan() (*QueryPlan, error) {
 	}
 	var child logicalNode
 	resultColumn := p.stmt.ResultColumns[0]
-	if resultColumn.All {
+	if resultColumn.Count {
+		child = &countNode{
+			tableName: tableName,
+			rootPage:  rootPageNumber,
+		}
+	} else if resultColumn.All {
 		scanColumns, err := p.getScanColumns()
 		if err != nil {
 			return nil, err
@@ -94,11 +101,37 @@ func (p *selectQueryPlanner) getQueryPlan() (*QueryPlan, error) {
 			rootPage:    rootPageNumber,
 			scanColumns: scanColumns,
 		}
-	} else {
-		child = &countNode{
-			tableName: tableName,
-			rootPage:  rootPageNumber,
+	} else if resultColumn.Expression != nil {
+		switch e := resultColumn.Expression.(type) {
+		case *compiler.ColumnRef:
+			if e.Table == "" {
+				// TODO should do better at checking no table
+				e.Table = p.stmt.From.TableName
+			}
+			cols, err := p.catalog.GetColumns(e.Table)
+			if err != nil {
+				return nil, err
+			}
+			colIdx := slices.Index(cols, e.Column)
+			pkCol, err := p.catalog.GetPrimaryKeyColumn(e.Table)
+			if err != nil {
+				return nil, err
+			}
+			child = &scanNode{
+				tableName: e.Table,
+				rootPage:  rootPageNumber,
+				scanColumns: []scanColumn{
+					{
+						isPrimaryKey: pkCol == e.Column,
+						colIdx:       colIdx,
+					},
+				},
+			}
+		default:
+			panic("unhandled expression")
 		}
+	} else {
+		panic("unhandled result column")
 	}
 	projections, err := p.getProjections()
 	if err != nil {
@@ -139,6 +172,13 @@ func (p *selectQueryPlanner) getScanColumns() ([]scanColumn, error) {
 
 func (p *selectQueryPlanner) getProjections() ([]projection, error) {
 	resultColumn := p.stmt.ResultColumns[0]
+	if resultColumn.Count {
+		return []projection{
+			{
+				isCount: true,
+			},
+		}, nil
+	}
 	if resultColumn.All {
 		cols, err := p.catalog.GetColumns(p.stmt.From.TableName)
 		if err != nil {
@@ -152,12 +192,17 @@ func (p *selectQueryPlanner) getProjections() ([]projection, error) {
 		}
 		return projections, nil
 	}
-	if resultColumn.Count {
-		return []projection{
-			{
-				isCount: true,
-			},
-		}, nil
+	if resultColumn.Expression != nil {
+		switch e := resultColumn.Expression.(type) {
+		case *compiler.ColumnRef:
+			return []projection{
+				{
+					colName: e.Column,
+				},
+			}, nil
+		default:
+			panic("unhandled expression")
+		}
 	}
 	panic("unhandled projection")
 }

planner/select_test.go

@@ -70,6 +70,44 @@ func TestGetPlan(t *testing.T) {
 	}
 }
 
+func TestGetPlanSelectColumn(t *testing.T) {
+	expectedCommands := []vm.Command{
+		&vm.InitCmd{P2: 1},
+		&vm.TransactionCmd{P1: 0},
+		&vm.OpenReadCmd{P1: 1, P2: 2},
+		&vm.RewindCmd{P1: 1, P2: 7},
+		&vm.RowIdCmd{P1: 1, P2: 1},
+		&vm.ResultRowCmd{P1: 1, P2: 1},
+		&vm.NextCmd{P1: 1, P2: 4},
+		&vm.HaltCmd{},
+	}
+	ast := &compiler.SelectStmt{
+		StmtBase: &compiler.StmtBase{},
+		From: &compiler.From{
+			TableName: "foo",
+		},
+		ResultColumns: []compiler.ResultColumn{
+			{
+				Expression: &compiler.ColumnRef{
+					Column: "id",
+				},
+			},
+		},
+	}
+	mockCatalog := &mockSelectCatalog{}
+	mockCatalog.primaryKeyColumnName = "id"
+	mockCatalog.columns = []string{"name", "id", "age"}
+	plan, err := NewSelect(mockCatalog, ast).ExecutionPlan()
+	if err != nil {
+		t.Errorf("expected no err got err %s", err)
+	}
+	for i, c := range expectedCommands {
+		if !reflect.DeepEqual(c, plan.Commands[i]) {
+			t.Errorf("got %#v want %#v", plan.Commands[i], c)
+		}
+	}
+}
+
 func TestGetPlanPKMiddleOrdinal(t *testing.T) {
 	expectedCommands := []vm.Command{
 		&vm.InitCmd{P2: 1},